Well you've had all night now - presume you are done.
Interesting leak.
It's not a steep roof...6/12 and one spot about 21" was dished in. A seam in the felt ran right through the middle of it and the shingle line did too.
It looks like it has been weeping for a long time making the dish worse. When we got the monsoon the other day I guess it puddled there and instead of weeping, it dripped.
I had to pull the shingles up, replace the sheathing, put down new felt and some roof cement to seal the edge, then re-shingle that area.
I also noticed some wear around the starter shingles that I'm going to fix while I'm up there.